However, healthcare policy experts told FierceHealthcare that the legislation, which the House passed on a razor-thin margin, will face an uphill battle on its journey to the president's desk.

“It’s very clear that what passed the House is not going to pass the Senate,” said Julius Hobson, a healthcare lobbyist and attorney with the Washington, D.C., law firm Polsinelli.

Julius Hobson

For one, the amendments made to the bill may not comply with the Senate’s so-called Byrd Rule that governs what can be included in a budget reconciliation measure, he said.

In addition, Hobson pointed out that members of the Senate have already suggested that they are going to start from scratch rather than take up the House version of the bill.

“I’ve talked to a couple of key senators on this,” he said, “and to the last one, they said, ‘we will definitely have amendments,’ sort of laughing, as if to say, you know, ‘we’re not taking up that crap.’”

Sally Pipes, president and CEO of the right-leaning Pacific Research Institute, also pointed out that conservative senators such as Rand Paul, Mike Lee and Ted Cruz might prove difficult to win over.

Thus, “I think that it could be changed significantly at the Senate level,” she said.

Major hurdle in Medicaid

One of the major sticking points, Hobson said, will not be the AHCA’s individual market changes—which were the focus of amendments to the bill—but rather what it has in store for the Medicaid program.

“Medicaid will be a bigger issue in the Senate than it was in the House,” Hobson predicted.

For example, Sen. Rob Portman, R-Ohio, and Sen. Lisa Murkowski, R-Alaska, whose states both embraced Medicaid expansion, have already come out against what the House did in terms of cuts to the program, he noted.

Vivan Ho

Vivian Ho, who chairs the health economics department at Rice’s Baker Institute for Public Policy, pointed out that only does the AHCA gut the Affordable Care Act’s Medicaid expansion, it also scales back the Medicaid program that existed pre-ACA.

Indeed, when it scored the original House bill, the Congressional Budget Office estimated that it would reduce Medicaid outlays by $880 billion in the next 10 years.

“This is going to put a tremendous burden on states to try and cover healthcare for low-income people who qualify for Medicaid,” she said. “It won’t look so bad at the beginning; it’s the way the law is written, it will compound year by year, and so within 10 years, these programs are going to be suffering a great deal.”

Even America’s Health Insurance Plans, the industry’s largest trade group, was concerned about the bill’s implications for the Medicaid program.

“The American Health Care Act needs important improvements to better protect low- and moderate-income families who rely on Medicaid or buy their own coverage,” AHIP President and CEO Marilyn Tavenner wrote in a statement. “If changes are made to criteria for who is covered by Medicaid, we need to give people more time to adjust—and more time for the individual market to stabilize.”

Every American deserves affordable, accessible, coverage and care, including those w/ pre-existing conditions https://t.co/dnNEG0uZ4z

Waiting on the CBO

Though the Congressional Budget Office scored the original version of the AHCA, it has not yet evaluated the revised bill.

“I think it’s highly irresponsible for anyone to approve legislation when they don’t know how much it’s going to affect the number of Americans who will be able to buy insurance and how much it’s going to cost,” Ho said.

The CBO is expected to score the revised bill while Congress is out on recess, according to Hobson, who noted that if the agency predicts the latest version will be costlier or cover fewer people, Republicans will feel the political consequences.

“I can see the Democrats’ ads right now, as they go after certain House members, to say, ‘this one voted to take away your health insurance,’” he said.

Sally Pipes

The Alliance of Community Health Plans, which represents nonprofit insurers, also wants to know more about the bill the House just passed.

“We are eager to see scoring from the nonpartisan Congressional Budget Office to better understand the full implications of the bill on millions of Americans across the country,” Ceci Connolly, the group’s president and CEO, wrote in a statement.

For her part, Pipes was worried that the amendments made to the bill are going to add to the costs. “That has implications of course, for what the Senate is going to do,” she added.

If the waiver system put in place by an amendment authored by Rep. Tom MacArthur, R-N.J., and Rep. Mark Meadows, R-N.C., survives the Senate’s scrutiny, Pipes is also concerned about what that will mean for the individual market. Some states will apply to opt out of the Affordable Care Act’s community rating and essential health benefits rules, she said, but larger states like California and New York likely won’t.